Terminal assembly with regions of differing solderability

ABSTRACT

An intercoupling component is provided which permits reliable, non-permanent electrical connection between a first substrate and a second substrate. The intercoupling component includes a socket terminal having a first end, and a second end opposed to the first end. An axial hole extends inward from the second end, and an electrically conductive core member is disposed within the axial hole. The core member is formed of a different material than the socket terminal body, and is sized and shaped to obstruct the hole. In addition, the first end of the socket terminal is configured to receive a pin terminal, and the second end of the socket terminal is configured to be received within a hole in a printed circuit board.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of and claims priority toU.S. Pat. No. 8,119,926, filed on Apr. 1, 2009. The entire contents ofthe patent are hereby fully incorporated by reference.

BACKGROUND OF THE INVENTION

This invention relates to making electrical connections betweenelectrical contacts of a first substrate and electrical contacts of asecond substrate.

Ball grid array (BGA) and land grid array (LGA) integrated circuit (IC)packages are becoming increasingly popular. With a BGA package, forexample, the rounded solder balls of the BGA are generally soldereddirectly to corresponding surface mount pads of a printed circuit boardrather than to plated thru-holes which receive pins from, for example, apin grid array (PGA) package. BGA packages are advantageous due to theability to provide a high density of connections and low profiles. Inaddition, BGAs, with their very short distance between the package andthe printed circuit board, have low inductances and therefore have farsuperior electrical performance relative to leaded devices. Oncesoldered to a printed circuit board, however, BGAs are difficult toreplace or interchange.

Intercoupling components are used to allow particular IC packages to bereliably interchanged without permanent connection to a printed circuitboard. More recently, adaptors for use with BGA and LGA packages havebeen developed to allow these packages to be non-permanently connected(e.g., for testing) to a printed circuit board.

SUMMARY

This invention relates to an intercoupling component to permit reliable,non-permanent electrical connection between a first substrate and asecond substrate. More particularly, the intercoupling componentincludes an electrically conductive terminal assembly including a firstend and a second end opposed to the first end. The first and second endsof the terminal assembly are configured to receive, and form anelectrical connection with, a solder ball. An axial hole extends inwardfrom each of the first end and the second end of the terminal, and anelectrically conductive core member is disposed within each hole. Thecore members are sized and shaped to obstruct the hole. In addition, atleast an outer surface of the core members includes a first material andat least an outer surface of the body includes a second material, thefirst material having greater solderability than the second material.

In one aspect, an electrical terminal is provided that includes anelectrically conductive terminal body. The terminal body includes afirst end and an axial hole extending inward from the first end. Thefirst end is configured to receive a first solder ball. The terminalbody includes a second end opposed to the first end, and the second endis configured to receive a second solder ball. The electrical terminalfurther includes an electrically conductive core member disposed withinthe hole. The core member is sized and shaped to obstruct the hole. Inaddition, at least an outer surface of the core member includes a firstmaterial and at least an outer surface of the body includes a secondmaterial, and the first material has greater solderability than thesecond material.

The electrical terminal includes one or more of the following features:

The first material is one of gold, gold alloy, tin, tin-lead alloy, andpalladium-nickel alloy. The second material is one of nickel and nickelalloy. The core member is fixed within the through hole. The core memberincludes a shank portion received within the axial hole, and a headportion connected to the shank portion. The head portion is disposedoutside the axial hole and includes a side which faces toward the firstend. The core member is an elongate cylindrical member having a firstend and a second end, and the first end is provided with a firstdiameter, and the second end is provided with a second diameter. Thesecond diameter is greater than the first diameter, and the first end isfitted within the axial hole.

In some aspects, an intercoupling component of the type used toelectrically connect a first substrate with a second substrate isprovided. The intercoupling component includes an insulating supportmember having an array of apertures. Each aperture extends from a firstsurface of the insulating support member to an opposite second surfaceof the insulating support member, and each aperture is configured toreceive a terminal assembly. The intercoupling component also includes aplurality of terminal assemblies which provide electrical connectionsbetween connection regions of the first substrate and respectivecorresponding connection regions of the second substrate. A terminalassembly is disposed in at least some of the apertures. Each terminalassembly includes an electrically conductive terminal body. The terminalbody includes a first end and an axial hole extending inward from thefirst end. The first end is configured to receive a first solder ball.The terminal body also includes a second end opposed to the first end,and the second end is configured to receive a second solder ball. Eachterminal assembly also includes an electrically conductive core memberdisposed within the hole. The core member is sized and shaped toobstruct the hole. At least an outer surface of the core member includesa first material and at least an outer surface of the body includes asecond material, and the first material has greater solderability thanthe second material.

The intercoupling component may include one or more of the followingfeatures:

The first material is one of gold, gold alloy, tin, tin-lead alloy, andpalladium-nickel alloy. The second material is one of nickel and nickelalloy. The core member is fixed within the through hole. The insulativesupport member includes a thin polyamide sheet. The core member ispositioned within the axial hole such that an end face of the coremember is flush with respect to the first end of the body. The coremember includes a shank portion received within the axial hole, and ahead portion connected to the shank portion. The head portion isdisposed outside the axial hole and includes a side which faces towardthe first end.

In some aspects, a method of forming an electrical terminal is provided.The method includes the following method steps: Forming a body using ascrew machining process, the body including a first end and an axialhole extending inward from the first end. Forming a core member using ascrew machining process separately from the body, the core member sizedto fit within and obstruct the axial hole. Assembling the core memberwithin the axial hole so that the hole is obstructed by the core member.In the method, at least an outer surface of the core member includes afirst material and at least an outer surface of the body includes asecond material, and the first material has greater solderability thanthe second material.

The method may further include plating at least the outer surface of thecore member with the first material, and plating at least the outersurface of the body with the second material.

In some aspects, a method of connecting a ball grid array of a firstsubstrate, the ball grid array including solder balls of a first type,to electrical connections on a second substrate using an intercouplingdevice including solder balls of a second type, is provided. The methodsteps include: Providing the device including a plurality of individualelectrical terminals supported on an insulative sheet member. Arrangingthe first substrate on an upward facing surface of the device such thateach solder ball of the ball grid array contacts a correspondingterminal of the device. Heating the device and first substrate in anenvironment having a temperature within a first range of temperatures toform an electrical connection between each solder ball of the ball gridarray and the corresponding terminal. Inverting the device so that thefirst substrate resides below the device. Providing a solder ball of thesecond type on an upward facing surface of one or more of the terminals.Heating the device, first substrate, and solder balls of the second typein an environment having a temperature within a second range oftemperatures. The second range of temperatures is lower than the firstrange of temperatures, so as to form an electrical connection betweeneach solder ball of the second type and the corresponding terminal.Inverting the device so that the first substrate resides above thedevice. Arranging the device on an upper surface of the second substratesuch that each solder ball of the second type contacts an electricalcontact element of the second substrate. Heating the device, firstsubstrate, and second substrate in an environment having a temperaturewithin the second range of temperatures so as to form an electricalconnection between each solder ball of the second type and thecorresponding electrical contact elements of the second substrate.

The method may include one or more of the following features:

The solder balls of the first type are lead-free, and the solder ballsof the second type are a tin-lead alloy. The second range oftemperatures includes a range of temperatures at which the lead-freesolder balls of the ball grid array do not reflow.

In some aspects, an electrical intercoupling device is provided. Thedevice includes an electrically insulative support member including anarray of through holes. The through holes extend between opposed firstand second surfaces of the insulative support member. The distancebetween the first and second surfaces define a thickness of the supportmember. The device further includes plural electrically conductiveterminals. Each terminal is disposed in a through hole and includes aterminal head, a terminal body extending from the terminal head and aretaining member that is separable from the terminal body. The terminalbody includes a length that is greater than the thickness of theinsulative support member, and a cross section that is configured suchthat an outer surface of the terminal body is spaced apart from an innersurface of the corresponding through hole. The terminal head has adimension that is larger than the hole dimension. In addition, eachterminal is disposed in a corresponding through hole of the array ofthrough holes such that the terminal body resides in the hole and theretaining member is disposed on an end of the terminal body and isconfigured to cooperate with the terminal head to maintain the terminalwithin the hole.

The device may include one or more of the following features:

At least an outer surface of the retaining member includes a firstmaterial and at least an outer surface of the terminal body includes asecond material. At least an outer surface of the terminal body includesa solderable material and at least an outer surface of the retainingmember includes a material that is resistive to solder flow. At least anouter surface of the retaining member includes nickel. The retainingmember is annular in shape, has an inner diameter of substantially thesame dimension as the terminal body, and has an outer dimension that islarger than the hole dimension. The terminal head is positioned adjacentthe first surface of the insulative member, and the retaining member ispositioned adjacent the second surface of the insulative member. Theterminal body comprises a first end integral with the terminal head, andan opposed second end, the second end of the terminal body includingplug formed of a material different than the material of the terminalbody. The second end of the terminal body terminates in the plug. Thesecond end of the terminal body has a cross-sectional dimension that isless than that of the first end of the terminal body, and the plug hasthe same cross-sectional dimension as that of the second end. At leastan outer surface of the plug includes a solderable material and at leastan outer surface of the retaining member includes a material that isresistive to solder flow.

In some aspects, an electrical intercoupling device is provided. Thedevice includes an electrically insulative support member including anarray of through holes. The through holes extend between opposed firstand second surfaces of the insulative support member. The distancebetween the first and second surfaces defines a thickness of the supportmember. The device also includes plural electrically conductiveterminals. Each terminal is disposed in a through hole and includes aterminal head, a terminal body having a first end integral with theterminal head, and an opposed second end. The second end of the terminalbody terminates in a plug formed of a material different than thematerial of the terminal body.

The device may include one or more of the following features:

Each terminal further includes a retaining member, the terminal bodyincludes a length that is greater than the thickness of the insulativesupport member, and the terminal head has a dimension that is largerthan the hole dimension. In addition, each terminal is disposed in acorresponding through hole of the array of through holes such that theterminal body resides in the hole. In addition, the retaining member isdisposed on the second end of the terminal body and is configured tocooperate with the terminal head to maintain the terminal within thehole. At least an outer surface of the plug includes a solderablematerial and at least an outer surface of the retaining member includesa material that is resistive to solder flow. The retaining member isannular in shape, has an inner diameter of substantially the samedimension as the second end of the terminal body, and has an outerdimension that is larger than the through hole dimension.

In some aspects, an apparatus is provided that includes an electricallyconductive socket terminal. The socket terminal includes an electricallyconductive body, the body including a first end and a first axial holeextending inward from the first end, and a second end opposed to thefirst end, and a second axial hole extending inward from the second end.The socket terminal also includes a resilient contact member disposed inthe first axial hole, and an electrically conductive core member sizedand shaped to obstruct the second axial hole, the core member disposedwithin the second axial hole such that the second axial hole isobstructed, where being obstructed refers to full and complete blockingof the hole whereby fluid flow between the core member and an innersurface of the hole is prevented.

The apparatus may include one or more of the following features:

At least an outer surface of the core member includes a first materialand at least an outer surface of the body includes a second material,the first material having greater solderability than the secondmaterial. The first material is one of gold, gold alloy, tin, tin-leadalloy, and palladium-nickel alloy. The second material is one of tin,tin alloy, nickel and nickel alloy. At least an outer surface of thecore member includes a first material and at least an outer surface ofthe body includes a second material, and the first material is differentfrom the second material. The core member includes a core member firstend, the core member first end sized and shaped to obstruct the secondaxial hole, the core member first end disposed within the second axialhole such that the second axial hole is obstructed, and a core membersecond end opposed to the core member first end, the core member secondend disposed outside the body. The core member second end comprises apin. The core member further comprises an outwardly protruding flangeportion disposed between the core member first end and the core membersecond end, and the core member second end comprises a pin thatprotrudes from the flange portion on a side of the flange portion thatis opposed to the core member first end. The flange portion has agreater cross-sectional dimension than the corresponding cross-sectionaldimension of the core member first end and the core member second end.The flange portion is disposed outside the second axial hole andincludes a side which faces toward the body second end.

The apparatus may include one or more of the following additionalfeatures:

The apparatus further includes an insulating support member including anarray of apertures, each aperture extending from a first surface of theinsulating support member to an opposite second surface of theinsulating support member, each aperture configured to receive one ofthe socket terminals; and one or more of the socket terminals disposedin respective apertures. The apparatus further includes a pin adaptorincluding a plurality of pins, each pin of the pin adaptor configured toengaged with a corresponding one of the socket terminals such that thepin is received in the first axial hole of the corresponding one of thesocket terminals and forms an electrical connection with the body viathe resilient contact member, the apparatus providing electricalconnections between connection regions of a first substrate andrespective corresponding connection regions of a second substrate. Atleast an outer surface of the core member includes a first material andat least an outer surface of the body includes a second material, andthe first material is different from the second material. At least anouter surface of the core member includes a first material and at leastan outer surface of the body includes a second material, the firstmaterial having greater solderability than the second material. Thefirst material is one of gold, gold alloy, tin, tin-lead alloy, andpalladium-nickel alloy. The second material is one of tin, tin alloy,nickel and nickel alloy. The core member includes a core member firstend, the core member first end sized and shaped to obstruct the secondaxial hole, the core member first end disposed within the second axialhole such that the second axial hole is obstructed, and a core membersecond end opposed to the core member first end, the core member secondend disposed outside the socket terminal.

The apparatus may include one or more of the following additionalfeatures:

The resilient contact member is configured to receive and form anelectrical connection with a pin contact. The first end of the socketterminal is configured to receive a pin terminal, and the second end ofthe socket terminal is configured to be received within a hole in aprinted circuit board. At least an outer surface of the core memberincludes a first material and at least an outer surface of the bodyincludes a second material, and the first material is different from thesecond material.

Because the terminal assemblies disclosed herein are constructed byassembling a core member within a terminal body, manufacturing costs aregreater than for terminal assemblies which are of single-piececonstruction and require no assembly. However, the increasedmanufacturing costs associated with the assembly of the core memberwithin the terminal body are offset by reductions in material costs.That is, the cost savings associated with plating only the core memberwith a material such as gold, rather than the entire terminal assemblywith a material such as gold, more than compensates for the cost ofassembling the core member within the terminal body.

Modes for carrying out the present invention are explained below byreference to an embodiment of the present invention shown in theattached drawings. The above-mentioned object, other objects,characteristics and advantages of the present invention will becomeapparent from the detailed description of the embodiment of theinvention presented below in conjunction with the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of an intercoupling component ofthe type used to couple a printed circuit board to a BGA package.

FIG. 2 is a partial side sectional view of the intercoupling componentof FIG. 1.

FIG. 3 is a partial side sectional view of another embodiment of anintercoupling component.

FIG. 4 is a partial side sectional view of another embodiment of anintercoupling component.

FIG. 5 is a partial side sectional view of another embodiment of anintercoupling component.

FIG. 6 is a perspective view of the core member of the terminal of FIG.5.

FIG. 7 is a partial side sectional view of another embodiment of anintercoupling component.

FIG. 8 is a partial side sectional view of another embodiment of anintercoupling component.

FIG. 9 is a side view of another embodiment of an intercouplingcomponent.

FIG. 10 is a side sectional view of a terminal of the intercouplingcomponent of FIG. 9.

FIG. 11 is a side sectional view of another embodiment of a terminal ofthe intercoupling component of FIG. 9.

FIG. 12 is a side sectional view of another embodiment of a terminal ofthe intercoupling component of FIG. 9.

FIG. 13 is a side sectional view of another embodiment of a terminal ofthe intercoupling component of FIG. 9.

FIG. 14 is a side view of another embodiment of an intercouplingcomponent.

FIG. 15 is a perspective view of a terminal of the intercouplingcomponent of FIG. 14.

FIG. 16 is a perspective view of another embodiment of a terminal of theintercoupling component of FIG. 14.

FIGS. 17-20 are partial side-sectional views of the intercouplingcomponent of FIG. 14 illustrating the method of connecting a BGA packageusing lead-free solder balls to electrical connections on a printedcircuit board using lead-containing solder balls.

FIG. 21 is a partial side sectional view of a socket adaptor for theintercoupling component of FIG. 2, illustrating an alternativeembodiment of a socket.

FIG. 22 is a partial side sectional view of a socket adaptor for theintercoupling component of FIG. 2, illustrating another alternativeembodiment of a socket.

FIG. 23 is a partial side sectional view of a socket adaptor for theintercoupling component of FIG. 2, illustrating another alternativeembodiment of a socket.

DETAILED DESCRIPTION

Referring to FIG. 1, a BGA socket converter assembly 320 forintercoupling a BGA integrated circuit package 4 to a printed circuitboard 6 is shown. The BGA socket converter assembly 320, serving as anintercoupling component, includes a socket adaptor 302 and a pin adaptor301. The socket adaptor 302 includes a first electrically insulativesupport member 310 for supporting sockets 330, each of which is receivedwithin a corresponding one of an array of holes 316 in the firstinsulative member 310. The array of holes 316 are provided in a patterncorresponding to a footprint of rounded solder balls (not shown) of BGApackage 4 as well as a footprint of surface mount pads 7 of printedcircuit board 6. The pin adaptor 301 includes a second electricallyinsulative support member 360 supporting pins 260 positioned within anarray of holes 366. Like the array of holes 316 in the first insulativemember, the array of holes 366 in the second insulative member 360 isprovided in a pattern corresponding to a footprint of the rounded solderballs of the BGA package 4 as well as a footprint of the surface mountpads 7 of the printed circuit board 6.

When the solder balls of the BGA package 4 are soldered to the pins 260of pin adaptor 301, the BGA package 4 is converted to a high density pingrid array (PGA). When the pin adaptor 301 is assembled with the socketadaptor 302, pins 260 are received within sockets 330. As will bediscussed in detail below with respect to FIG. 2, each socket 330includes a solder ball 12 attached to its lower end 342 to provide anidentical mating condition to the surface mount pads 7 of the printedcircuit board 6 as would have been the case if the BGA package 4 hadbeen connected directly to the circuit board. Thus, the converterassembly 320 permits the BGA package 4 to be non-permanentlyelectrically intercoupled with the printed circuit board 6.

As seen in FIG. 2, each pin 260 cooperatively engages a correspondingsocket 330 to provide an electrical connection between a surface mountpad 5 of BGA package 4 and a corresponding surface mount pad 7 ofprinted circuit board 6.

The pin 260 includes a pin head 262 fixed within the hole 366, and anintegral stem 266 that extends outward from the pin head 262. The pin260 is configured to receive a solder ball 12 at one end of the pin head262. In the illustrated orientation of the socket converter assembly320, the solder ball 12 is received on a first, upper end 268 of the pinhead 262, and the stem 266 extends from a second, opposed, lower end 270of the pin head 262.

The socket 330 includes a socket base 336 having an end 342 configuredto receive a solder ball 12, and a socket body 332 extending integrallyfrom the socket base 336. The socket body 332 is supported on theelectrically insulative support member 310. The socket body 332 includesa socket cavity 334 opening at an end 340 of the socket body 332 opposedto the base end 342, and a resilient contact member 348 is disposedwithin the cavity 334. The resilient contact member 348 is fixed withincavity 334 and forms an electrical connection with the socket body 332along mutually contacting surfaces. In use, the stem 266 of the pin 260is slidably received within, and forms an electrical connection with,the resilient contact member 348.

An axial hole 338 is provided at, and extends axially inward from, theend 342 of the socket base 336. A core member 246 is disposed within theaxial hole 338.

The core member 246 is electrically conductive and is sized and shapedto obstruct the axial hole 338, where the term obstruct as used hereinrefers to a full and complete blocking of, or stopping-up of, the hole,whereby fluid flow between the core members 246 and the inner surface ofthe axial hole 338 is prevented. The core member 246 is fixed within theaxial hole 338 and forms an electrical connection with the socket head336 along mutually contacting surfaces. The core member 246 ispositioned within the axial hole 338 so that an end face 245 of the coremember 246 lies flush with the outer surface of the terminal structure.That is, in the socket 330, the core member 246 lies flush with the end342 of the socket base 336. Alternatively, the core member 246 may bepositioned within the axial hole 338 so that an end face 245 of the coremember 246 is spaced slightly inward relative to an end face of theterminal structure, forming a shallow depression (not shown) at thelocation of the core member 246. The depression can be useful inpositioning and retaining the solder ball 12 relative to the socket baseend 342.

The pin 260, the socket 330 and core members 246 are formed ofelectrically conductive materials. During solder reflow, solder isprevented from flowing along a peripheral side of the socket 330 byselective use of materials in the manufacture thereof. In particular,the socket 330 is formed of, coated, or plated with a material that isresistive to solder flow or has relatively low solderability. Inaddition, the core member 246 is formed of, coated, or plated withmaterial that has relatively high solderability in that it promotessolder flow, forms a good electrical contact and bonds well with asolder ball. As a result, when a solder ball 12, positioned adjacent toan end 342 of the socket 330, is heated to cause the solder to flow, thesolder does not flow along a peripheral side of the socket 330 due tothe chemical response of the solder to the materials of the terminalbody. Instead, solder is generally maintained in the vicinity of thecore member 246.

In some embodiments, the socket 330 is manufactured entirely of anelectrically conductive material that is resistive to solder flow or hasrelatively low solderability as compared to the material used tomanufacture the core members 246. Such materials will be referred toherein as “solder resistive materials.” Solder resistive materialsgenerally inhibit solder flow and do not bond well with the appliedsolder. Examples of solder resistive materials include nickel and nickelalloys. In other embodiments, the socket 330 is manufactured of anelectrically conductive material such as brass or copper, and is thencoated or plated with the material that is resistive to solder flow orhas relatively low solderability.

In some embodiments, the core member 246 is manufactured entirely of anelectrically conductive material that is easily solderable, and hasbetter solderability properties than that of the socket 330. Suchmaterials will be referred to herein as “solderable materials.” Examplesof solderable materials include gold and gold alloys. In otherembodiments, the core member 246 is manufactured of an electricallyconductive material such as brass or copper, and is then coated orplated with the material that easily solderable, and has bettersolderability properties than that of the terminal body. Examples ofsolderable materials which would be used as coating or plating materialsare gold, gold alloys, tin, tin-lead alloys, and palladium-nickelalloys.

In some embodiments, the pin 260 and contact member 348 are manufacturedentirely of a solderable materials. In other embodiments, the pin 260and/or contact member 348 are manufactured of an electrically conductivematerial such as brass or copper, and are then coated or plated with asolderable material.

Although respective examples of solderable materials and solderresistive materials are listed above, other materials are applicable,and selection of material will depend on, at least, the type of solderemployed.

Referring now to FIG. 3, another embodiment of the socket converterassembly is shown. In this embodiment, the pin adaptor 301of FIG. 2 isused with a socket adaptor 602 to provide a socket converter assembly620. The socket adaptor 602 includes a socket 630 supported on theelectrically insulative support member 310 as described in more detailbelow. As in the previous embodiment, in the socket converter assembly620, each pin 260 cooperatively engages a corresponding socket 630 toprovide an electrical connection between a surface mount pad 5 of BGApackage 4 and a corresponding surface mount pad 7 of printed circuitboard 6.

The socket 630 includes a socket base 636 having an end 642 configuredto receive a solder ball 12, and a socket body 632 extending integrallyfrom the socket base 636. The socket body 632 includes a socket cavity634 opening at an end 640 of the socket body 632 opposed to the base end642, and a resilient contact member 348 is fixed within the cavity 634so as to form an electrical connection with the socket body 632 alongmutually contacting surfaces. In use, the stem 266 of the pin 260 isreceived within, and forms an electrical connection with, the resilientcontact member 348.

The first end 640 of the socket body is provided with a widened portion641 having an outer dimension (e.g. diameter) that is greater than thatof the socket body 632 and the hole 316. The second end 642 of socket630 includes a narrowed portion 643 having a smaller cross-sectionaldimension (e.g. diameter) than the socket body 632. An annular ring 560is fitted on the periphery of the narrowed portion 643, and has an outerdimension (e.g. diameter) greater than that of the hole 316. The annularring 560 cooperates with widened portion 641 of the socket body 632 tomaintain the socket 630 within the hole 316 and to substantially preventvertical movement of the socket 630 relative to support member 310. Thisconfiguration permits the socket 630 to have smaller cross-sectionaldimensions that that of the hole 316 to an extent that a gap g existsbetween the socket 630 and the hole 316, a feature that reduces stresswithin the support member 310, and in turn can prevent warping of thesocket adaptor 602.

Annular ring 560 encircles the narrowed portion 643. In addition, thenarrowed portion 643 is dimensioned to be fitted within the innerdiameter of the annular ring 560 so that fluid flow is prevented betweenthe narrowed portion 643 and the inner diameter surface of the annularring 560. In some embodiments, the socket 630, including the narrowedportion 643, is formed of, coated, or plated with an electricallyconductive, solderable material, and the annular ring 560 is formed of asolder-resistive material. By selection of materials in this way, solderis permitted to flow and connect to the exposed end face 642 of thenarrowed portion 643, but is substantially prevented from flowing alongthe inner diameter surfaces of the annular ring 560.

Referring now to FIG. 4, another embodiment of the intercoupling deviceis shown. In this embodiment, the pin adaptor 301 of FIG. 2 is used witha socket adaptor 202 to provide a socket converter assembly 220. Thesocket adaptor 202 includes a plurality of sockets 230 supported bysupport members 40, 50, in an arrangement which corresponds to thepattern of surface mount pads 5, 7 of the substrates 4, 6 to beinterconnected. As in the previous embodiments, in the socket converterassembly 220, each pin 260 cooperatively engages a corresponding socket230 to provide an electrical connection between a surface mount pad 5 ofBGA package 4 and a corresponding surface mount pad 7 of printed circuitboard 6.

The support members 40, 50 include an array of through holes 46, 56 eachdimensioned to receive a socket 230 and arranged in the patterndescribed above. The support members 40, 50 are formed of a thin sheet(e.g. 5-7 mils) of insulative material. In some embodiments, the sheetmay be somewhat flexible as embodied by a polyamide film. The polyamidefilm may be, for example, a Kapton® sheet (Kapton is a registeredtrademark of E.I. DuPont de Nemours & Co., Wilimington, Del.). In otherembodiments, the sheet may be sufficiently rigid to retain a planarconfiguration when supported in a cantilevered manner, as embodied by amolded plastic sheet of FR4 printed circuit board material.

The lower end of the socket 230 includes a socket base 236 configured toreceive a solder ball 12, and a socket body 232 extends from the socketbase 236. The socket body 232 includes a socket cavity 234 opening at anupper end 240 of the socket body 232 opposed to the base end 242, and aresilient contact member 348 is fixed within the cavity 234 so as toform an electrical connection with the socket body 232 along mutuallycontacting surfaces. In use, the stem 266 of the pin 260 is receivedwithin, and forms an electrical connection with, the resilient contactmember 348.

Circumferential grooves 244, provided about the periphery of each of thebase end 236 and upper end 240, cooperatively engage the edge portionsof the insulative support members 40, 50 at each respective hole 46, 56.That is, holes 46, 56 of the insulative support members 40, 50 are sizedand shaped to correspond to the size and shape of the grooves 244 suchthat portions of the insulative support members reside withincircumferential grooves 244. As a result, the axial position of theinsulative support members 40, 50 relative to the socket 230 is easilymaintained.

An axial hole 238 is provided at, and extends axially inward from, theend 242 of the socket base 236, and a core member 246 is disposed withinthe axial hole 238.

The core member 246 is sized and shaped to obstruct the axial hole 238,and forms an electrical connection with the socket base 236 alongmutually contacting surfaces. As in the previous embodiment, the pin260, the socket 230, and the core member 246 are each formed ofelectrically conductive materials. In socket converter assembly 220,solder is prevented from flowing along peripheral sides of the socketbase 236 during solder reflow by selective use of materials inmanufacturing the socket 230. In particular, the socket 230 is formedof, coated, or plated with a material that is resistive to solder flowor has relatively low solderability. In addition, the core member 246 isformed of, coated, or plated with material that has relatively highsolderability in that it promotes solder flow, forms a good electricalcontact and bonds well with a solder ball. As a result, during use whena solder ball 12, positioned adjacent to an end face 242 of the socket230 is heated to cause the solder to flow, the solder does not flowalong a peripheral side of the socket base 236 due to the due to thechemical response of the solder to the materials of these members, andis generally maintained in the vicinity of the core member 246.

Referring now to FIG. 5, another embodiment of the intercoupling deviceis shown. In this embodiment, the pin adaptor 301of FIG. 2 is used witha socket adaptor 702 to provide a socket converter assembly 720. Thesocket adaptor 702 includes a plurality of sockets 730 supported by asupport member 315 in an arrangement which corresponds to the pattern ofsurface mount pads 5, 7 of the substrates 4, 6 to be interconnected. Asin the previous embodiments, in the socket converter assembly 720, eachpin 260 cooperatively engages a corresponding socket 730 to provide anelectrical connection between a surface mount pad 5 of BGA package 4 anda corresponding surface mount pad 7 of printed circuit board 6.

The support member 315 is formed of an electrically insulative material.In some embodiments, support member 315 is of single-piece construction.In the illustrated embodiment, support member 315 is of two-piececonstruction and includes a base layer 312, and an outer layer 314pressed onto an outward-facing surface of the base layer 312. The baselayer 312 and outer layer 314 may be formed of the same insulativematerial, or formed of different insulative materials. The outer layer314 is thin relative to the base layer 312. For example, the base layer312 may be in the range of 5 to 20 times the thickness of the outerlayer 314. The support member 315 is provided having an overallthickness that is about or slightly less than the axial length l3 of thesocket 730. Each layer 312, 314 of the support member 315 includes arespective array of through holes 316, 318 arranged in the patterndescribed above. The through holes 316 of base layer 312 are dimensionedto correspond to the shape and size of the socket 730, and the throughholes 318 of the outer layer 314 are dimensioned to correspond to theshape and size of a shank portion 352 of the socket core 350 (FIG. 6,described below).

The socket 730 includes a socket base 736, and a socket body 732extending from the socket base 736. The socket body 732 includes asocket cavity 734 opening at the first end 740 of the socket body 732. Aresilient contact member 348 is fixed within the cavity 734 so as toform an electrical connection with the socket base 736 along mutuallycontacting surfaces. In use, the stem 266 of the pin 260 is receivedwithin, and forms an electrical connection with, the resilient contactmember 348.

A socket axial hole 738 is provided at, and extends axially inward from,the end 742 of the socket base 736. A shaped socket core 350 is disposedwithin the socket axial hole 738. As seen in FIG. 6, the shaped coremember 350 includes a shank portion 352 sized to be received within thesocket axial hole 738, and a head portion 354 connected to an end of theshank portion 352. In some embodiments, the shank portion 352 is fittedwithin the socket axial hole 738. When the socket 730 is received withinthe support member 315, the head portion 354 is disposed outside thethrough hole 318 of the outer layer 314. The shank portion 352 of theshaped core member 350 has a shank cross-sectional dimension d3 (e.g.diameter), the head portion 354 has a head cross-sectional dimension d4(e.g. diameter), and the head cross-sectional dimension d4 is greaterthan the shank cross-sectional dimension d3. As shown in FIG. 5, whenthe shank portion 352 is received within the socket axial hole 738, thehead portion 354 is disposed outside the axial hole 738, and extends ina plane that is perpendicular to an axial direction of the shank portion352 so that a side 356 of the head portion 354 is spaced apart from andfaces toward the end 742 of the socket base 736. The outer layer 314 ofthe support member 315 is interposed between the side 356 of the headportion 354 and the end 742 of the socket base 736.

The core member 350 is electrically conductive, and the shank portion352 is sized and shaped to obstruct the socket axial hole 738 and forman electrical connection with the socket base 736 along mutuallycontacting surfaces. As in previous embodiments, the socket 730 and thecore member 350 are each formed of electrically conductive materials. Insocket 730, solder is prevented from flowing along a peripheral side ofthe socket base 736 during solder reflow by selective use of materials.In particular, the socket 730, including the socket base 736, is formedof, coated, or plated with a material that is resistive to solder flowor has relatively low solderability. In addition, the core member 350 isformed of, coated, or plated with material that has relatively highsolderability in that it promotes solder flow, forms a good electricalcontact and bonds well with a solder ball. As a result, during use whena solder ball 12 positioned adjacent to a lower side 358 of the coremember 350 is heated to cause the solder to flow, the solder does notflow along a peripheral side of the socket base 736 due to the due tothe chemical response of the solder to the materials of these members,and is generally maintained in the vicinity of the head portion 354 ofthe core member 350. In some embodiments, solder retention in thevicinity of the head portion 354 may be enhanced by use of a solderresist coating an outward-facing surface of the outer layer 314 of thesupport member 315.

Referring now to FIG. 7, another embodiment of the intercoupling deviceis shown. In this embodiment, the pin adaptor 301 of FIG. 2 is used witha socket adaptor 502 to provide a socket converter assembly 520. Thesocket adaptor 502 includes a plurality of sockets 530 supported by asupport member 510 in an arrangement which corresponds to the pattern ofsurface mount pads 5, 7 of the substrates 4, 6 to be interconnected. Asin the previous embodiments, in the socket converter assembly 520, eachpin 260 cooperatively engages a corresponding socket 530 to provide anelectrical connection between a surface mount pad 5 of BGA package 4 anda corresponding surface mount pad 7 of printed circuit board 6.

The socket 530 is supported on one of an array of holes 516 formed in aninsulative support member 510, and includes a socket base 536, and asocket body 532 extending from the socket base 536. The socket body 532includes a socket cavity 534 opening at the first end 540 of the socketbody 532. A resilient contact member 348 is fixed within the cavity 534so as to form an electrical connection with the socket base 536 alongmutually contacting surfaces. In use, the stem 266 of the pin 260 isreceived within, and forms an electrical connection with, the resilientcontact member 348.

The first end 540 of the socket body 532 is provided with a widenedportion 541 having an outer dimension (e.g. diameter) that is greaterthan that of the socket body 532 and the hole 516. The second end 542 ofsocket 530 includes a narrowed portion 543 having a smallercross-sectional dimension (e.g. diameter) than the socket body 532. Anannular ring 560 is fitted on the narrowed portion 543, and has an outerdimension (e.g. diameter) greater than that of the hole 516. The annularring 560 cooperates with widened portion 541 of the socket body 532 toprevent vertical movement of the socket 530 relative to support member510. This configuration permits the socket 530 to have smallercross-sectional dimensions than that of the hole 516 to an extent that agap g exists between the socket 530 and the hole 516, a feature thatreduces stress within the support member 510, and in turn can preventwarping of the intercoupling device 520.

The narrowed portion 543 terminates at a plug 550. In some embodiments,the plug 550 is formed separately from the socket 530, and is fixed tothe narrowed portion 543 by conventional means in such a way as toprovide an electrically conductive path therethrough. For example, insome embodiments, an interference fit between the annular ring 560 andthe plug 550, and between the annular ring 560 and the narrowed portion543 retains the plug 550 in electrical contact with the narrowed portion543.

The annular ring 560 encircles both the narrowed portion 543 and plug550. In addition, the narrowed portion 543 and plug 550 are dimensionedto be fitted within inner diameter of the annular ring 560 so that fluidflow is prevented between either of the narrowed portion 543 or plug550, and the inner surface of the annular ring 560. In some embodiments,the socket 530 including the narrowed portion 543 are formed of anelectrically conductive material such as brass, the plug 550 is formedof a solderable material, and the annular ring 560 is formed of, orplated with a solder-resistive material. By selection of materials inthis way, solder is permitted to flow and connect to the plug 550, butis substantially prevented from flowing along the surfaces of theannular ring 560.

Referring now to FIG. 8, another embodiment of the intercoupling deviceis shown. In this embodiment, the pin adaptor 301of FIG. 2 is used witha socket adaptor 402 to provide a socket converter assembly 420. Thesocket adaptor 402 includes a plurality of sockets 430 supported bysupport members 40, 50 (described above with reference to FIG. 4) in anarrangement which corresponds to the pattern of surface mount pads 5, 7of the substrates 4, 6 to be interconnected. As in the previousembodiments, in the socket converter assembly 420, each pin 260cooperatively engages a corresponding socket 430 to provide anelectrical connection between a surface mount pad 5 of BGA package 4 anda corresponding surface mount pad 7 of printed circuit board 6.

The socket 430 includes a socket base 436, and a socket body 432extending from the socket base 436. The first, upper end 440 of socket430 is supported in a corresponding hole 46 of the support member 40 andthe second, lower end 442 of socket 430 is supported in a correspondinghole 56 of the support member 50.

A circumferential groove 444 is provided about the periphery of firstend 440, which cooperatively engages the edge portion of the insulativesupport members 40 at each respective hole 46. That is, holes 46 of theinsulative support members 40 are sized and shaped to correspond to thesize and shape of the grooves 444 such that portions of the insulativesupport members reside within circumferential grooves 444.

The socket body 432 includes a socket cavity 434 opening at the firstend 440 of the socket body 432. A resilient contact member 348 is fixedwithin the cavity 434 so as to form an electrical connection with thesocket base 436 along mutually contacting surfaces. In use, the stem 266of the pin 260 is received within, and forms an electrical connectionwith, the resilient contact member 348.

The second end 442 of socket 430 includes a narrowed portion 443 havinga smaller cross-sectional dimension (e.g. diameter) than the socket body432. The holes 56 of the insulative support member 50 are sized andshaped to substantially correspond to the size and shape of the narrowedportion 443, and in use, the narrowed portion 443 is received in acorresponding hole 56. The narrowed portion 443 terminates at a plug450.

An annular ring 460 is fitted about the narrowed portion 443 and plug450, and has an outer dimension (e.g. diameter) greater than that of thehole 56. The annular ring 460 prevents vertical movement of the socket430 relative to support member 50. This configuration permits thenarrowed portion 443 of socket 430 to have a smaller cross-sectionaldimension that that of the hole 56 to an extent that a gap existsbetween the narrowed portion 443 and the hole 56, a feature that reducesstress within the support member 50, and in turn can prevent warping ofthe intercoupling device.

The annular ring 460 encircles both the narrowed portion 443 and plug450. In addition, the narrowed portion 443 and plug 450 are dimensionedto be fitted within the annular ring 460 so that fluid flow is preventedbetween either of the narrowed portion 443 or plug 450, and the innersurface of the annular ring 460. In some embodiments, the socket 430,including the narrowed portion 443, is formed of an electricallyconductive material such as brass, the plug 450 is formed of, coated, orplated with a solderable material, and the annular ring 460 is formed ofa solder-resistive material. By selection of materials in this way,solder is permitted to flow and connect to the plug 450, but issubstantially prevented from flowing along the surfaces of the annularring 460 or the socket body 432.

Referring now to FIG. 9, an intercoupling device 20, used to provide anelectrical connection between electrical contacts (e.g. surface mountpads 5) of a first substrate (e.g. BGA package 4) and correspondingelectrical contacts (e.g. surface mount pads 7) of a second substrate(e.g. printed circuit board 6), will now be described. The intercouplingdevice 20 includes a plurality of electrically conductive, single-pieceterminals 80, a support member 40 which supports a first end(illustrated here as the upper end) 88 of each terminal 80, and asupport member 50 which supports a second end (illustrated here as thelower end) 90 of each terminal 80. The terminals 80 are supported by thesupport members 40, 50 in an arrangement which corresponds to thepattern of surface mount pads 5, 7 of the substrates 4, 6 to beinterconnected.

The support members 40, 50 are substantially similar to those describedabove with respect to FIG. 4, and their description is not repeatedhere.

Each terminal 80 includes an electrically conductive terminal body 82.In the embodiment illustrated in FIGS. 8-10, the terminal body 82 is anelongate member. For example, the axial length l1 of the terminal body82 is at least twice the cross-sectional dimension (e.g. diameter d1) ofthe terminal body 82. In some embodiments, the terminal body 82 isgenerally cylindrical, although the cross-sectional shape of theterminal body 82 is not limited to a circular shape. Each of the firstand second ends 88, 90 is configured to receive a solder ball 12.

Circumferential grooves 83 may be provided adjacent to each of the firstand second ends 88, 90, which cooperatively engage the edge portions ofthe insulative support members 40, 50 at each respective hole 46, 56.That is, holes 46, 56 of the insulative support members 40, 50 are sizedand shaped to correspond to the size and shape of the groove 83, suchthat portions of the insulative support members reside withincircumferential grooves 83. As a result, the axial position of theinsulative support members 40, 50 relative to the terminal body 82 iseasily maintained.

As seen in FIG. 10, a first axial hole 84 is provided at, and extendsaxially inward from, the first end 88 of the terminal body 82.Similarly, a second axial hole 86 is provided at, and extends axiallyinward from, the second end 90 of the terminal body 82. A core member 70is disposed within each of the first axial hole 84 and second axial hole86.

The core members 70 are electrically conductive and are sized and shapedto obstruct the respective axial hole 84, 86, whereby fluid flow betweenthe core member 70 and the inner surface of the respective axial hole84, 86 is prevented. The core members 70 may be fixed within therespective axial hole 84, 86 and form an electrical connection with theterminal body 82 along mutually contacting surfaces. The core members 70may be positioned within the respective axial hole 84, 86 so that an endface 76 of the core member 70 lies flush with the corresponding end faceof the terminal body 82 (FIGS. 10, 12).

Alternatively, the core members 70 may be positioned within therespective axial hole 84, 86 so that an end face 76 of the core member70 is spaced slightly inward relative to an end face of the terminalbody 82, forming a shallow depression at the location of the core member70 (FIG. 11). The depression can be useful in positioning and retainingthe solder ball 12 relative to the terminal 80.

As discussed above, both the terminal body 82 and core members 70 areformed of electrically conductive materials. In terminal 80, solder isprevented from flowing along a peripheral side 92 of the terminal body82 during solder reflow by selective use of materials in manufacturingthe terminal 80. In particular, terminal body 82 is formed of, coated,or plated with a material that is resistive to solder flow or hasrelatively low solderability. In addition, core members 70 are formedof, coated, or plated with material that has relatively highsolderability in that it promotes solder flow, forms a good electricalcontact and bonds well with a solder ball. As a result, during use whena solder ball 12, positioned adjacent to an end face of the terminal 80,is heated to cause the solder to flow, the solder does not flow along aperipheral side 92 of the terminal body 82 due to the chemical responseof the solder to the materials of the terminal body 82, and is generallymaintained in the vicinity of the core members 70.

In some embodiments, the terminal body 82 is manufactured entirely of anelectrically conductive material that is resistive to solder flow or hasrelatively low solderability as compared to the material used tomanufacture the core members 70. In other embodiments, the terminal body82 is manufactured of an electrically conductive material such as brassor copper, and is then coated or plated with the material that isresistive to solder flow or has relatively low solderability.

In some embodiments, the core member 70 is manufactured entirely of anelectrically conductive material that is easily solderable, and hasbetter solderability properties than that of the terminal body 82. Inother embodiments, the core member 70 is manufactured of an electricallyconductive material such as brass or copper, and is then coated orplated with the material that easily solderable, and has bettersolderability properties than that of the terminal body 82.

Referring now to FIG. 12, in some embodiments, a terminal 80′ mayinclude a single axial through hole 84′, and core members 70 areprovided within the through hole 84′ such that a first core member 70 isdisposed adjacent to the first end 88 of the terminal body 82′, and asecond core member 70 is disposed adjacent to the second end 90 of theterminal body 82′. As in earlier embodiments, the core members 70 areelectrically conductive and are sized and shaped to obstruct therespective axial hole 84′. In addition, the core members 70 are formedof, coated or plated with a solderable material, and the terminal body82′ is formed of, coated or plated a solder resistive material.

Referring now to FIG. 13, in some embodiments, a terminal 80″ mayinclude a single axial through hole 84′, and a single, elongate coremember 70′ is provided within the through hole 84′ such that theelongate core member 70′ extends from the first end 88 of the terminalbody 82′ to the second end 90 of the terminal body 82′. As in earlierembodiments, the elongate core member 70′ is electrically conductive andis sized and shaped to obstruct the respective axial hole 84. Inaddition, the core member 70′ is formed of, coated or plated with asolderable material, and the terminal body 82′ is formed of, coated orplated with a solder resistive material.

Referring now to FIGS. 14-16, another embodiment of the intercouplingdevice is shown. Intercoupling device 120 is used to provide anelectrical connection between surface mount pads of BGA package 4 andcorresponding surface mount pads of printed circuit board 6. Theintercoupling device 120 includes a plurality of electrically conductiveterminals 180 supported by a single support member 40, in an arrangementwhich corresponds to the pattern of surface mount pads 5, 7 of thesubstrates 4, 6 to be interconnected.

Each terminal 180 includes an electrically conductive terminal body 182.The terminal body 182 is a member in which the axial length l2 of theterminal body 182 is less than the cross-sectional dimension (e.g.diameter d2) of the terminal body 182, whereby the terminal body 182 isa substantially disk-shaped member. In some embodiments, the terminalbody 182 is generally cylindrical, although the cross-sectional shape ofthe terminal body 182 is not limited to a circular shape. The terminalbody 182 has a first end 188, and a second end 190 opposed to the firstend 188. Each of the first and second ends 188, 190 is configured toreceive a solder ball 12.

As seen in FIG. 15, an axial through hole 184 is provided in theterminal body 182, and a core member 170 is provided within the throughhole 184 such that the core member 170 extends from the first end 188 ofthe terminal body 182 to the second end 190 of the terminal body 182. Asin earlier embodiments, the core member 170 is electrically conductiveand is sized and shaped to obstruct the axial hole 184, forming anelectrical connection with the terminal body 182 along mutuallycontacting surfaces. In addition, the core member 170 is formed of,coated, or plated with a solderable material, and the terminal body 182is formed of, coated or plated with a solder resistive material.

The core member 170 may be positioned within the axial hole 184 so thatone or both end faces 176 of the core member 170 lie flush with thecorresponding end face of the terminal body 182 (FIG. 15).Alternatively, the core member 170 may be positioned within the axialhole 184 so that the end faces 176 of the core member 170 are spacedslightly inward relative to an end face of the terminal body 182,forming a shallow depression at the location of the core member 170(FIG. 16).

A method of forming the electrical terminals 80, 180 will now bedescribed.

The terminals 80, 180 are each formed individually. In addition, theterminal body 82, 182 is formed separately from the core members 70,170. In some embodiments, the terminal body 82, 182 is formed using ascrew machining process, including formation of the axial hole 84, 86,184 in one or both ends. The core members 70, 170 may be formed using ascrew machining process, or alternatively may be formed using otherprocesses including stamping or riveting.

In some embodiments, the terminal body 82, 182 and core members 70, 170are formed of an electrically conductive material such as brass. Anouter surface of the terminal body 82, 182 is then plated or coated witha solder resistive material, and the outer surface of the core members70, 170 is plated or coated with a solderable material.

Then, the core members 70, 170 are assembled within the correspondingaxial holes of the terminal body 82, 182 so that the axial hole isobstructed.

In the converter assembly 220, 320, 420, 520, 620, 720 (FIGS. 2-5 and7-8) which employs an assembly of a pin and a socket to provide anelectrical terminal, the socket 230, 330, 430, 530, 630, 730 is formedseparately from its respective core (plug) member 246, 350, 450, 550and/or annular ring 460, 560, as well as from the pin 260. The socket230, 330, 430, 530, 630, 730 and annular ring 460, 560 (if required) arethen plated or coated with a solder resistive material. The pin 260 andcore (plug) member 246, 350, 450, 550 are plated or coated with asolderable material.

The core (plug) members 246, 350, 450, 550 and annular ring 460, 560 (ifrequired) are then assembled with the corresponding socket body 230,330, 430, 530, 630, 730 as described above.

By this procedure, at least an outer surface of the pin 260 and core(plug) member 70, 170, 246, 350, 450, 550 includes a first material andat least an outer surface of the body 82, 182, 232, 332, 432, 532, 632and/or annular ring 460, 560 includes a second material, the firstmaterial having greater solderability (being more solderable) than thesecond material.

Recent regulatory efforts to limit certain hazardous substances in somegeographic areas and/or in some industries, such as the Restriction ofHazardous Substances in Electrical and Electronic Equipment (RoHS), haveresulted in inconsistencies in the products that are manufactured, suchthat some electronic components, including IC packages and/or printedcircuit boards, are compliant with regulations and some are not. Thus,it can be advantageous to provide an intercoupling device which permits,for example, a lead-free component to be assembled to a lead-containingcomponent. A method of connecting a lead-free substrate (e.g. BGApackage 4) using lead-free solder balls 12 a, to electrical connectionson a second, lead-containing substrate (e.g. printed circuit board 6)using lead-containing solder balls 12 b is accomplished using theintercoupling devices described above. The method will be describedherein with reference to FIGS. 17-20 using the intercoupling device 120as an example.

The connecting method includes the following method steps:

The intercoupling device 120 is provided which includes a plurality ofindividual electrical terminals 180 supported on an insulative sheetmember 40, the terminals arranged in a pattern corresponding to that ofthe electrical connections of the substrates 4, 6 to be connected. InFIG. 17, only two terminals 180 are shown for simplicity ofillustration. However, it is understood that the number and arrangementof terminals 180 may correspond to the number and arrangement ofelectrical contacts of one or both substrates 4, 6.

The first substrate (BGA package 4) is arranged on an upward-facingsurface of the intercoupling device 120 such that each lead-free solderball 12 a of the ball grid array contacts a corresponding terminal 180(FIG. 18). The lead free solder balls 12 a are formed, for example, of atin-silver-copper alloy.

The intercoupling device 120 and BGA package 4 are placed in anenvironment having a temperature within a first range of temperatures.The first range of temperatures will depend on the specific material(s)used to form solder ball 12 a, and is selected to be appropriate forcausing reflow of the solder ball 12 a described above and for formingan electrical connection between each solder ball 12 a of the ball gridarray and the corresponding terminal 180, while being sufficiently lowto avoid causing damage to the BGA package 4. For a lead-free solderball 12 a formed of a tin-silver-copper alloy, the corresponding firsttemperature range is about 235-245 degrees Celsius.

The intercoupling device 120 is then inverted so that the BGA package 4resides below the device (FIG. 19).

Lead-containing solder balls 12 b are provided on upward facing surfacesof one or more of the terminals 180. The lead-containing solder balls 12b may be formed of a tin-lead alloy.

With the lead-containing solder balls 12 b provided on the upward facingsurfaces of the one or more terminals 180, the intercoupling device 120,BGA package 4, and solder balls 12 b are then heated in an environmenthaving a temperature within a second range of temperatures. The secondrange of temperatures will depend on the specific materials used to formthe lead-containing solder balls 12 b, and is selected to be sufficientto permit the lead-containing solder balls 12 b to bond to correspondingterminals 180, but insufficient to cause reflow of the lead-free solderballs 12 a. For a lead-containing solder ball 12 b formed of a tin-leadalloy, the corresponding second range of temperatures is about 200-210degrees Celsius. In this step, duration of heating is sufficiently shortto prevent complete reflow of the lead-containing solder balls 12 b, andis sufficiently long to permit an electrical connection to beestablished between each lead-containing solder ball 12 b and thecorresponding terminal 180.

The intercoupling device 120 is then inverted so that the BGA package 4resides above the device (FIG. 20).

The intercoupling device is arranged on an upper surface of the printedcircuit board 6 such that each lead-containing solder ball 12 b contactsan electrical contact element of the printed circuit board 6.

The BGA package 4, the intercoupling device 120, and the printed circuitboard 6 are heated in an environment having a temperature within thesecond range of temperatures until an electrical connection is formedbetween each lead-containing solder ball 12 b and the correspondingelectrical contact elements of the printed circuit board 6.

Referring now to FIG. 21, a socket adaptor 802 of another embodiment ofthe intercoupling device is shown. In this embodiment, the pin adaptor301 of FIG. 2 can be used with the socket adaptor 802 to provide asocket converter assembly. The socket adaptor 802 includes a pluralityof sockets 830 supported by a support member 310 in an arrangement whichcorresponds to the pattern of surface mount pads 5 or pin-receivingconnectors (not shown) of the substrates 4, 6 to be interconnected. In amanner similar to the previous embodiments, in the socket converterassembly, each pin 260 cooperatively engages a corresponding socket 830to provide an electrical connection between a surface mount pad 5 of BGApackage 4 and a corresponding pin-receiving connector (not shown) suchas a hole formed in a surface of a printed circuit board 6.

The socket 830 includes a socket body 832 and a socket core 950. Thesocket body 832 includes a first end 840, and a second end 842 opposedto the first end 840. A socket cavity 834 opens at the first end 840 ofthe socket body 832. A resilient contact member 348 is fixed within thecavity 834 so as to form an electrical connection with the socket body832 along mutually contacting surfaces. In use, the stem 266 of the pin260 is received within, and forms an electrical connection with, theresilient contact member 348. The socket body 832 further includes abase 836 adjacent to and including the second end 842, and a socketaxial hole 838 that extends axially inward from the second end 842 isprovided in the base 836.

The socket core 950 is disposed within the socket axial hole 838. Thesocket core 950 is pin-shaped, and includes a shank portion 952 sized tobe received within the socket axial hole 838, a flange portion 954 at anend of the shank portion 952, and a pin portion 956 extending from theflange portion 954 on a side of the flange portion 954 that is opposedto the shank portion 952. In some embodiments, the shank portion 952 isfitted or press-fit within the socket axial hole 838. When receivedwithin the socket axial hole 838, the shank portion 956 serves to orientand/or align the socket core 950 relative to the socket body 832.

In addition, the flange portion 954 and pin portion 956 of the socketcore 950 are disposed outside the socket base 836. The shank portion 952of the pin-shaped core member 950 has a shank cross-sectional dimensiond6 (e.g. diameter), the flange portion 954 has a flange cross-sectionaldimension d7 (e.g. diameter), and the pin portion 956 has a pincross-sectional dimension d8 (e.g. diameter). The flange cross-sectionaldimension d7 is greater than the shank cross-sectional dimension d6 andthe pin cross-sectional dimension d8. In the illustrated embodiment, theshank cross-sectional dimension d6 and the pin cross-sectional dimensiond8 are approximately the same. When the shank portion 952 is receivedwithin the socket axial hole 838, the flange portion 954 is disposedoutside the axial hole 838, and abuts the socket base end face 842. Inparticular, the flange portion 954 serves as a stop member that limitsthe depth of insertion of the socket core 950 within the socket 830.

In contrast to previous embodiments, in which the socket base 336 andcore member 246, 350, 450, 550 are configured to receive a solder ball,the pin portion 956 of the socket core 950 is configured to be receivedin a hole in a printed circuit board. The pin portion 956 forms anelectrical connection with the interior surface of the hole throughdirect contact with the interior surface of the hole or through indirectcontact via solder paste provided within the hole. In some embodiments,the pin portion 956 includes surface features (not shown) such as knurlsor resilient protrusions that permit and/or enhance contact with theinterior surface of the hole. Alternatively, the pin portion 956 of thesocket core 950 is configured to be received in a secondary socketmember that is connectable to a printed circuit board or integratedcircuit package.

The core member 950 is electrically conductive, and the shank portion952 is sized and shaped to obstruct the socket axial hole 838 and forman electrical connection with the socket base 836 along mutuallycontacting surfaces. As in previous embodiments, the socket 830 and thecore member 950 are each formed of electrically conductive materials.The socket 830 and the core member 950 are formed of differentmaterials.

In some embodiments, the socket 830 is formed of, coated, or plated witha material that is resistive to solder flow or has relatively lowsolderability. In these embodiments, the core member 950 is formed of,coated, or plated with material that has relatively high solderabilityin that it promotes solder flow, forms a good electrical contact andbonds well with solder. As a result, during use when solder paste orother solder mass that is positioned adjacent to the pin portion 956 ofthe core member 950 is heated to cause the solder to flow, the solderdoes not flow along a peripheral side of the socket base 836 due to thedue to the chemical response of the solder to the materials of thesemembers, and is generally maintained in the vicinity of the flangeportion 954 and pin portion 956 of the core member 950. In someembodiments, during use, the pin portion 956 forms an electricalconnection without solder, for example, via direct physical contact.

In some embodiments, the socket 830 is formed of, coated, or plated withtin, tin-lead alloy, nickel or nickel alloy, and the core member 950 isformed of, coated, or plated with gold, gold alloy, tin, tin-lead alloy,and palladium-nickel alloy.

In the illustrated embodiment, the socket cavity 834, which opens at thefirst end 840 of the socket 830, and the socket axial hole 838, whichopens at the second end 842 of the socket 830, intersect to formcontinuous opening 844 from the first end 840 to the base end 842. Inparticular, the socket cavity 834 has a larger cross-sectional dimensionthan the socket axial hole 838, whereby the continuous opening 844 isnon-uniform in dimension along the direction from the first end 840 tothe second end 842 of the socket 830.

Referring to FIG. 22, it is understood that the socket adaptor 802 isnot limited to this configuration. For example, an alternativeembodiment socket adaptor 802′ includes sockets 830′ which are similarto the socket 830 in form and function except that the socket cavity834′, which opens at the first end 840′ of the socket 830′, and thesocket axial hole 838′, which opens at the base end 842′ of the socket830′, intersect to form continuous opening 844′ from the first end 840′to the base end 842′. In this embodiment, the socket cavity 834′ has thesame cross-sectional dimension as the socket axial hole 838′, wherebythe continuous opening 844′ is uniform in dimension along the directionfrom the first end 840′ to the base end 842′ of the socket 830′.Accordingly, the dimensions of the shank portion 952′ of the socket core950′ are adapted to correspond to the dimensions of the socket axialhole 838′. In this example, the shank cross-sectional dimension d6 isgreater than the pin cross-sectional dimension d8.

Referring to FIG. 23, another alternative embodiment socket adaptor 802″includes sockets 830″ which are similar to the socket 830 in form andfunction except that the socket cavity 834″, which opens at the firstend 840″ of the socket 830″, and the socket axial hole 838″, which opensat the base end 842″ of the socket 830″, do not intersect. In thisembodiment, the socket cavity 834″ has the same cross-sectionaldimension as the socket axial hole 838″, but the respective openings834″, 838″are separated by a socket mid-portion 835″. As in the previousexample, the dimensions of the shank portion 952″ of the socket core950″ are adapted to correspond to the dimensions of the socket axialhole 838″.

In the illustrated embodiment, the socket 830 is dimensioned so thatwhen the socket 830 is received within the support member 310, thesocket base 836 is disposed outside the support member through hole 316.The socket 830 is not limited to this configuration, and the dimensionsof the socket 830 and/or the support member 310 may be adjusted so thatthe socket base 836 is disposed within the through hole 316. Forexample, in some embodiments, the second end 842 may be aligned with thesurface of the support member 310.

Selected illustrative embodiments of the invention are described abovein some detail. It should be understood that only structures considerednecessary for clarifying the present invention have been describedherein. Other conventional structures, and those of ancillary andauxiliary components of the system, are assumed to be known andunderstood by those skilled in the art.

Moreover, while working examples of the present invention have beendescribed above, the present invention is not limited to the workingexamples described above, but various design alterations may be carriedout without departing from the present invention as set forth in theclaims.

For example, although the embodiments disclosed herein illustratedevices which intercouple a printed circuit board and a BGA package, itis understood that the devices can also be use to intercouple a firstprinted circuit board to a second printed circuit board, and/or a firstintegrated circuit package to a second integrated circuit package.

1. An apparatus comprising an electrically conductive socket terminal,the socket terminal including an electrically conductive body, the bodyincluding a first end and a first axial hole extending inward from thefirst end, and a second end opposed to the first end, and a second axialhole extending inward from the second end; a resilient contact memberdisposed in the first axial hole, and an electrically conductive coremember sized and shaped to obstruct the second axial hole, the coremember disposed within the second axial hole such that the second axialhole is obstructed, where being obstructed refers to full and completeblocking of the hole whereby fluid flow between the core member and aninner surface of the hole is prevented.
 2. The apparatus of claim 1,wherein at least an outer surface of the core member includes a firstmaterial and at least an outer surface of the body includes a secondmaterial, the first material having greater solderability than thesecond material.
 3. The apparatus of claim 2, wherein the first materialis one of gold, gold alloy, tin, tin-lead alloy, and palladium-nickelalloy.
 4. The apparatus of claim 2, wherein the second material is oneof nickel and nickel alloy.
 5. The apparatus of claim 2, wherein thesecond material is one of tin and tin alloy.
 6. The apparatus of claim 1wherein at least an outer surface of the core member includes a firstmaterial and at least an outer surface of the body includes a secondmaterial, and the first material is different from the second material.7. The apparatus of claim 1, wherein the core member comprises a coremember first end, the core member first end sized and shaped to obstructthe second axial hole, the core member first end disposed within thesecond axial hole such that the second axial hole is obstructed, and acore member second end opposed to the core member first end, the coremember second end disposed outside the body.
 8. The apparatus of claim7, wherein the core member second end comprises a pin.
 9. The apparatusof claim 7, wherein the core member further comprises an outwardlyprotruding flange portion disposed between the core member first end andthe core member second end, and the core member second end comprises apin that protrudes from the flange portion on a side of the flangeportion that is opposed to the core member first end.
 10. The apparatusof claim 9, wherein the flange portion has a greater cross-sectionaldimension than the corresponding cross-sectional dimension of the coremember first end and the core member second end.
 11. The apparatus ofclaim 9, wherein the flange portion is disposed outside the second axialhole and includes a side which faces toward the body second end.
 12. Theapparatus of claim 1, further comprising: an insulating support memberincluding an array of apertures, each aperture extending from a firstsurface of the insulating support member to an opposite second surfaceof the insulating support member, each aperture configured to receiveone of the socket terminals; and one or more of the socket terminalsdisposed in respective apertures.
 13. The apparatus of claim 12, furthercomprising a pin adaptor including a plurality of pins, each pin adaptorpin configured to engaged with a corresponding one of the socketterminals such that the pin adaptor pin is received in the first axialhole of the corresponding one of the socket terminals and forms anelectrical connection with the body via the resilient contact member,the apparatus providing electrical connections between connectionregions of a first substrate and respective corresponding connectionregions of a second substrate.
 14. The apparatus of claim 12 wherein atleast an outer surface of the core member includes a first material andat least an outer surface of the body includes a second material, andthe first material is different from the second material.
 15. Theapparatus of claim 12, wherein at least an outer surface of the coremember includes a first material and at least an outer surface of thebody includes a second material, the first material having greatersolderability than the second material.
 16. The apparatus of claim 15,wherein the first material is one of gold, gold alloy, tin, tin-leadalloy, and palladium-nickel alloy.
 17. The apparatus of claim 15,wherein the second material is one of nickel and nickel alloy.
 18. Theapparatus of claim 12, wherein the core member comprises a core memberfirst end, the core member first end sized and shaped to obstruct thesecond axial hole, the core member first end disposed within the secondaxial hole such that the second axial hole is obstructed, and a coremember second end opposed to the core member first end, the core membersecond end disposed outside the socket terminal.
 19. The apparatus ofclaim 1 wherein the resilient contact member is configured to receiveand form an electrical connection with a pin contact.
 20. The apparatusof claim 1 wherein the first end of the socket terminal is configured toreceive a pin terminal, and the second end of the socket terminal isconfigured to be received within a hole in a printed circuit board.